Pressure-resistant water-blocking layer and insulated cable with pressure-resistant water-blocking layer

Abstract

The invention belongs to the technical field of cable waterproof design, and particularly relates to a pressure-resistant water-blocking layer and an insulated cable with the pressure-resistant water-blocking layer, the pressure-resistant water-blocking layer is formed by wrapping water-blocking cloth in the insulated cable, and the water-blocking cloth comprises water-blocking powder and base cloth used for loading and supporting the water-blocking powder. The water-blocking powder is a cross-linked copolymer of vinyl benzene sulfonate and acrylate, and the water absorption capacity of the pressure-resistant water-blocking layer is increased through the measure, so that the expansion degree of the pressure-resistant water-blocking layer is further increased, the internal structure of the cable is further expanded and densified, a water seepage channel in the cable is more favorably blocked, and the service life of the cable is prolonged. And water is prevented from further permeating into the deep part of the cable, so that the operation of the cable in a water environment can be better guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of cable waterproof design, and particularly relates to a compression water-blocking layer and an insulated cable with the compression water-blocking layer. Background Art

[0002] Although several protective layers are successively coated outside the conductor core of the cable, many cables still have the risk of being eroded and penetrated by water. This not only affects the service life of each protective layer on the cable, but also may further form water trees on the insulating layer inside the cable and damage the insulating layer under the influence of the operating voltage, resulting in serious consequences such as power outages.

[0003] To prevent the insulating layer from getting damp and generating water trees, a water-blocking tape is commonly used as a protective layer for the insulating layer and the conductor core inside it in many cable structures. The water-blocking tape is filled with a water-blocking powder such as sodium polyacrylate. Due to its three-dimensional network molecular chain structure, it can adsorb water hundreds of times its own mass in the natural state. More importantly, after the water-blocking powder absorbs water, it can effectively block the water inlet gap or channel through volume expansion inside the cable, inhibiting further inward penetration of water.

[0004] For some cables buried underwater, not only are they surrounded by water in the water environment, but the cables are also constantly under the pressure of water pressure, so they face a greater risk of water seepage. In this regard, the applicant believes that it is necessary to further optimize and improve the water-blocking effect of the cable. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a compression water-blocking layer formed by winding a water-blocking cloth in an insulated cable. The water-blocking cloth includes a water-blocking powder and a base cloth for loading and supporting the water-blocking powder. The water-blocking powder is a cross-linked copolymer of vinyl benzene sulfonate and acrylate, and its cross-linking monomers include 15-30 parts by weight of vinyl benzene sulfonate, 70-85 parts by weight of acrylate, and 0.5-1.5 parts by weight of a cross-linking agent.

[0006] Preferably, the preparation method of the water-blocking powder is as follows: mix and disperse vinyl benzene sulfonate monomer, acrylate monomer, and cross-linking agent monomer in water to form a monomer solution; heat the monomer solution to 60°C - 80°C under stirring, and dropwise add an initiator solution thereto. After the dropping is completed, continue to react for a period of time, then dehydrate, dry, and pulverize.

[0007] Further, the vinyl benzene sulfonate monomer is sodium 4-vinyl benzene sulfonate.

[0008] Further, the acrylate monomer includes one or a combination of several of sodium acrylate, potassium acrylate, sodium methacrylate, and potassium methacrylate.

[0009] Further: The crosslinking monomer includes one or a combination of several of ethylene glycol dimethacrylate, ethylene glycol diacrylate, or dipropylene glycol diacrylate.

[0010] Although the solubility of these crosslinking monomers in water is very small, on the one hand, the amount of the crosslinking monomer used here is very small, and on the other hand, the vinylbenzenesulfonate monomer and acrylate monomer added to water together with the crosslinking monomer are soluble in water and have certain surfactant functions, thus ensuring the effective dispersion of the crosslinking monomer in water.

[0011] Further: The initiator solution is obtained by dissolving persulfate in water at a mass concentration of 2% - 4%.

[0012] Preferably: The water-blocking cloth is formed by bonding and spreading water-blocking powder on a base cloth with an adhesive.

[0013] Further: After uniformly coating an adhesive on the surface of the non-woven base cloth at a dosage of 40 - 60 g / m 2 the water-blocking powder is uniformly sprayed on the formed adhesive layer at a dosage of 30 - 100 g / m 2 dosage.

[0014] The present invention also provides an insulated cable having the above-mentioned compressive water-blocking layer. The insulated cable includes a conductor, a conductor shielding layer, an insulating layer, a compressive water-blocking layer, and a protective layer from the inside to the outside in terms of layer structure.

[0015] Preferably: The insulating layer is a crosslinked polyethylene layer, including 100 parts by weight of polyethylene, 10 - 25 parts by weight of polyolefin elastomer, 5 - 20 parts by weight of compatibilizer, 0.5 - 2 parts by weight of crosslinking agent, 1 - 5 parts by weight of lubricant, and 1 - 2 parts by weight of antioxidant.

[0016] Preferably: The protective layer is a crosslinked polypropylene layer, including 100 parts by weight of polypropylene, 5 - 15 parts by weight of polyolefin elastomer, 5 - 10 parts by weight of compatibilizer, 0.5 - 1.5 parts by weight of crosslinking agent, 1 - 3 parts by weight of lubricant, 0.5 - 1.5 parts by weight of antioxidant, and 0.1 - 0.5 parts by weight of light stabilizer.

[0017] Preferably: During the preparation and molding process of the insulated cable, first, the aluminum foil paper is uniformly wound tightly on the outer surface of the conductor as a conductor shielding layer coaxial with the conductor; the components of the insulating layer are melt-blended and then uniformly extruded and coated on the outer surface of the conductor shielding layer, and after sufficient cooling, an insulating layer coaxial with the conductor shielding layer is formed; the water-blocking cloth is uniformly wound tightly on the outer surface of the insulating layer as a compressive water-blocking layer coaxial with the insulating layer; the components of the protective layer are melt-blended and then uniformly extruded and coated on the outer surface of the compressive water-blocking layer, and after sufficient cooling, a protective layer coaxial with the compressive water-blocking layer is formed.

[0018] When forming the compression-resistant water-blocking layer by winding, the side of the base fabric sprayed with water-blocking powder is facing inwards and tightly wrapped to prevent the adhesive on the base fabric from failing due to the subsequent extrusion of the protective layer resin, which is still in a high-temperature state, onto the surface of the insulation layer after winding the side of the base fabric sprayed with water-blocking powder outwards, resulting in the water-blocking powder falling off the base fabric.

[0019] The beneficial effects of the present invention are as follows: Vinylbenzenesulfonate monomers and acrylate monomers are copolymerized and crosslinked in the water-blocking powder, thereby introducing a benzene ring structure into the crosslinked network. The benzene ring has the characteristics of large volume and rigidity, which is conducive to further expanding the crosslinked network, increasing the internal space structure of the crosslinked network, and allowing more water to enter the crosslinked network structure. At the same time, the sulfonate functional group carried on the benzene ring also has a high affinity for water, effectively compensating for the hydrophobicity of the benzene ring and maintaining the attraction trend of the crosslinked network to water. In summary, after the water absorption capacity of the water-blocking powder increases under the above measures, it can absorb more water penetrating into the cable, further increasing its own swelling degree, thereby further expanding and densifying the internal structure of the cable, which is more conducive to blocking the water seepage channels inside the cable and preventing water from further penetrating deep into the cable, thus better ensuring the operation of the cable in a water environment. Brief Description of the Drawings

[0020] Figure 1 It is a schematic diagram of the layer structure of the insulated cable of the present invention when it is a single-core cable. Among them, 1 - conductor, 2 - conductor shielding layer, 3 - insulation layer, 4 - compression-resistant water-blocking layer, 5 - protective layer. Detailed Embodiments

[0021] Example 1

[0022] At room temperature, 20 parts by weight of sodium 4-vinylbenzenesulfonate, 35 parts by weight of sodium acrylate, 45 parts by weight of sodium methacrylate, and 1 part by weight of ethylene glycol dimethacrylate are added to 300 parts by weight of water and stirred and dispersed thoroughly to form a monomer solution. Under stirring, the monomer solution is first heated to 60 °C and kept warm (controlling the subsequent temperature not lower than 60 °C), and then 20 parts by weight of an aqueous solution of potassium persulfate with a mass concentration of 2% is added dropwise thereto. The dropping is completed in 0.5 h. After the dropping is completed, the reaction continues for 3 h and then the stirring is stopped. The obtained reaction system is placed in an oven at 80 °C to dehydrate to constant weight, chopped, and then dried at 120 °C for 2 h. After cooling, it is further pulverized to 100 meshes to obtain the water-blocking powder.

[0023] On the surface of the polyester non-woven fabric base fabric, HY-101 glue is uniformly coated at a dosage of 40 g / m 2 and then the above-prepared water-blocking powder is coated at a dosage of 75 g / m 2The amount of the waterproof fabric was evenly sprayed on the above HY-101 glue layer, and the waterproof fabric was obtained after the HY-101 glue layer was fully dried. The water swelling ability of the waterproof fabric was tested, and the specific results are shown in Table 1.

[0024] Processing and forming of insulated cables:

[0025] First, wrap the aluminum foil evenly and tightly on the outer surface of the metal copper conductor to serve as a conductor shielding layer coaxially arranged with the conductor;

[0026] 100 parts by weight of polyethylene (218-W), 15 parts by weight of ethylene-octene copolymer elastomer (8150), 7 parts by weight of maleic anhydride grafted polyethylene compatibilizer, 1.5 parts by weight of dicumyl peroxide, 2 parts by weight of zinc stearate, and 1 part by weight of antioxidant 1010 are mixed, melted and uniformly extruded on the outer surface of the conductor shielding layer through a twin-screw extruder at 105-130° C., and after sufficient cooling, an insulating layer (thickness of about 1.6 mm, the same below) coaxially arranged with the conductor shielding layer is formed;

[0027] The non-woven fabric base fabric sprayed with water-blocking powder prepared in this embodiment (the side sprayed with water-blocking powder faces inward) is evenly wrapped tightly on the outer surface of the above-mentioned insulating layer (wrapping angle 30°, wrapping overlap rate 10%), as a pressure-resistant water-blocking layer coaxially arranged with the insulating layer;

[0028] 100 parts by weight of polypropylene (Yanshan Petrochemical 1396D), 10 parts by weight of ethylene-octene copolymer elastomer (8150), 5 parts by weight of maleic anhydride grafted polypropylene compatibilizer, 1 part by weight of dicumyl peroxide, 3 parts by weight of zinc stearate, 1 part by weight of antioxidant 1010, and 0.2 parts by weight of UV-531 are blended, melted and uniformly extruded on the outer surface of the above-mentioned pressure-resistant water-blocking layer at 160-190° C. through a twin-screw extruder, and after sufficient cooling, a protective layer (thickness of about 1.3 mm, the same below) coaxially arranged with the pressure-resistant water-blocking layer is formed.

[0029] Example 2

[0030] At room temperature, 25 parts by weight of sodium 4-vinylbenzene sulfonate, 25 parts by weight of sodium acrylate, 50 parts by weight of sodium methacrylate and 1 part by weight of ethylene glycol dimethacrylate are added to 350 parts by weight of water and stirred and dispersed sufficiently to prepare a monomer solution. Under stirring, the monomer solution is first heated to 65°C and kept warm (the subsequent temperature is controlled to be not lower than 65°C), and then a 2% aqueous solution of potassium persulfate is added dropwise thereto in a total of 15 parts by weight. The addition is completed within 0.5h, and the reaction is continued for 3h after the addition is completed before stopping the stirring. The obtained reaction system is placed in an oven at 80°C for dehydration to constant weight, chopped, and then placed at 120°C for drying for 2h, and then further crushed to 100 mesh after cooling to prepare a water-blocking powder.

[0031] On the surface of the polyester non-woven fabric base cloth, HY-101 glue is evenly coated according to the dosage of 30 g / m 2 After that, the water-blocking powder prepared above is evenly sprayed on the above-mentioned HY-101 glue layer according to the dosage of 70 g / m 2 After the HY-101 glue layer is fully dried and solidified, a water-blocking cloth is obtained, and the water swelling ability of the water-blocking cloth is detected. The specific results are shown in Table 1.

[0032] Processing and forming of the insulated cable:

[0033] First, the aluminum foil paper is evenly wound and tightly wrapped around the outer surface of the metal copper conductor as a conductor shielding layer coaxially arranged with the conductor;

[0034] After the components of the insulating layer in Example 1 are blended and melted evenly, they are extruded and coated on the outer surface of the above-mentioned conductor shielding layer, and after sufficient cooling, an insulating layer coaxially arranged with the conductor shielding layer is formed;

[0035] The non-woven fabric base cloth sprayed with water-blocking powder prepared in this example (with the side sprayed with water-blocking powder facing inward) is evenly wound and tightly wrapped around the outer surface of the above-mentioned insulating layer (wrapping angle 30°, wrapping overlap rate 10%) as a compressive water-blocking layer coaxially arranged with the insulating layer;

[0036] After the components of the protective layer in Example 1 are blended and melted evenly, they are extruded and coated on the outer surface of the above-mentioned compressive water-blocking layer, and after sufficient cooling, a protective layer coaxially arranged with the compressive water-blocking layer is formed.

[0037] Comparative Example 1

[0038] Replace 4-vinylbenzenesulfonate in the water-blocking powder with the sum of "sodium acrylate and sodium methacrylate" of equal weight, and the other components, specifications, and operations are the same as in Example 1:

[0039] At room temperature, 45 parts by weight of sodium acrylate, 55 parts by weight of sodium methacrylate, and 1 part by weight of ethylene glycol dimethacrylate are added to 300 parts by weight of water and stirred and dispersed sufficiently as a monomer solution; under stirring, the monomer solution is first heated to 60 °C and kept warm (controlling the subsequent temperature not lower than 60 °C), and then 20 parts by weight of an aqueous solution of potassium persulfate with a mass concentration of 2% is added dropwise thereto. The dropping is completed in 0.5 h. After the dropping is completed, the reaction continues for 3 h and then the stirring is stopped. The obtained reaction system is placed in an oven at 80 °C to be dehydrated to constant weight, chopped, and then dried at 120 °C for 2 h. After cooling, it is further pulverized to 100 meshes as the water-blocking powder.

[0040] On the surface of the polyester non-woven fabric base cloth, according to 40 g / m 2After evenly coating HY-101 glue in the amount specified, the water-blocking powder prepared above was evenly sprayed onto the above-mentioned HY-101 glue layer at a rate of 75 g / m 2 After the HY-101 glue layer was fully dried and solidified, a water-blocking cloth was obtained, and the water-swelling ability of the water-blocking cloth was tested. The specific results are shown in Table 1.

[0041] Processing and forming of insulated cables:

[0042] First, aluminum foil was evenly wound tightly around the outer surface of the metal copper conductor as a conductor shielding layer coaxially arranged with the conductor;

[0043] After blending the components of the insulating layer in Example 1, they were melt-extruded evenly onto the outer surface of the above-mentioned conductor shielding layer, and after sufficient cooling, an insulating layer coaxially arranged with the conductor shielding layer was formed;

[0044] The non-woven fabric base cloth sprayed with water-blocking powder prepared in this comparative example (with the side sprayed with water-blocking powder facing inwards) was evenly wound tightly around the outer surface of the above-mentioned insulating layer (winding angle 30°, winding overlap rate 10%) as a compressive water-blocking layer coaxially arranged with the insulating layer;

[0045] After blending the components of the protective layer in Example 1, they were melt-extruded evenly onto the outer surface of the above-mentioned compressive water-blocking layer, and after sufficient cooling, a protective layer coaxially arranged with the compressive water-blocking layer was formed.

[0046] Comparative Example 2

[0047] Replace "sodium 4-vinylbenzenesulfonate" in the water-blocking powder with an equimolar amount of "styrene", and the other components, specifications, and operations are the same as in Example 1:

[0048] At room temperature, 10 parts by weight of styrene, 35 parts by weight of sodium acrylate, 45 parts by weight of sodium methacrylate, and 1 part by weight of ethylene glycol dimethacrylate were added to 300 parts by weight of water and stirred and dispersed thoroughly to obtain a monomer solution (acrylate monomers are soluble in water and have a certain surfactant function, enabling a small amount of styrene to be emulsified and dispersed in water); under stirring, the monomer solution was first heated to 60 °C and kept warm (controlling the subsequent temperature not lower than 60 °C), and then 20 parts by weight of an aqueous solution of potassium persulfate with a mass concentration of 2% was added dropwise thereto. The dropping was completed in 0.5 h. After the dropping was completed, the reaction continued for 3 h and then the stirring was stopped. The resulting reaction system was placed in an oven at 80 °C to dehydrate to constant weight, chopped, and then dried at 120 °C for 2 h. After cooling, it was further pulverized to 100 mesh as the water-blocking powder.

[0049] On the surface of the polyester non-woven fabric base cloth, after evenly coating HY-101 glue in the amount specified at 40 g / m 2 the water-blocking powder prepared above was evenly sprayed onto it at a rate of 75 g / m2 The dosage of is evenly sprayed on the above-mentioned HY-101 glue layer. After the HY-101 glue layer is fully dried and solidified, a water-blocking cloth is obtained, and the water-swelling ability of the water-blocking cloth is detected. The specific results are shown in Table 1.

[0050] Processing and forming of insulated cables:

[0051] First, aluminum foil is evenly wound and tightly wrapped around the outer surface of the metal copper conductor as a conductor shielding layer coaxially arranged with the conductor.

[0052] After blending the components of the insulating layer in Example 1, they are uniformly extruded and melted on the outer surface of the above-mentioned conductor shielding layer, and after sufficient cooling, an insulating layer coaxially arranged with the conductor shielding layer is formed.

[0053] The non-woven fabric base cloth sprayed with water-blocking powder prepared in this comparative example (with the side sprayed with water-blocking powder facing inward) is evenly wound and tightly wrapped around the outer surface of the above-mentioned insulating layer (wrapping angle 30°, wrapping overlap rate 10%) as a compressive water-blocking layer coaxially arranged with the insulating layer.

[0054] After blending the components of the protective layer in Example 1, they are uniformly extruded and melted on the outer surface of the above-mentioned compressive water-blocking layer, and after sufficient cooling, a protective layer coaxially arranged with the compressive water-blocking layer is formed.

[0055] Table 1

[0056]

[0057] Each swelling height in Table 1 is detected in accordance with JB / T 10259-2014 (Appendix A). The test specimen is a circle with a diameter of 80 mm cut from the water-blocking cloth, so as to match the inner cavity size of the swelling height tester. After the side of the specimen sprayed with water-blocking powder is placed face-up on the bottom of the swelling height tester container, the lower cover plate is gently lowered to horizontally press the specimen (the pressure of the cover plate on the specimen is 100 Pa), and then 100 mL of deionized water is uniformly injected into the container (finished injecting in 10 s). Timing starts when the water injection begins. When the timing reaches 5 min, the distance of the upward displacement of the cover plate is recorded through the scale on the side of the container as the swelling height value (5 specimens are tested for each example and comparative example respectively, and the average value of the test results is taken).

[0058] The cables processed in each example and comparative example were respectively subjected to DC withstand voltage tests in water: A 5-meter-long cable was taken as a specimen, and the protective layers at both ends were stripped to expose the conductors. After bending the specimen into a U shape, it was vertically installed in a water tank through a fixing frame, and the conductors exposed at both ends of the specimen were made to protrude above the water surface by about 0.25 m. The distance from the water surface to the lowest point of the U-shaped cable specimen was about 1.7 m. The water temperature in the water tank was maintained at 25°C ± 2°C. After standing for 24 hours, an initial DC voltage of 120 V was applied to the specimen, and the DC voltage was uniformly increased to 1000 V at a rate of 1 V / s and then kept constant for 4 hours of continuous experiment. During this period, the leakage current values of the cable specimen were recorded every 30 minutes (3 specimens were tested for each example and comparative example respectively, and at the same time node, the average of the leakage currents of these three specimens was taken). The recorded results are shown in Table 2:

[0059] Table 2

[0060]

[0061] From the result comparison of Table 1 and Table 2 above, after introducing sodium 4-vinylbenzenesulfonate into the crosslinked network structure of the compressive water-blocking layer in this solution, the expansion of the compressive water-blocking layer after encountering water is more obvious. The applicant believes that this is jointly caused by the propping effect of the benzene ring in the structure of sodium 4-vinylbenzenesulfonate on the crosslinked network and the affinity of the sulfonate group for water; and when it is used as a waterproof tape for the cable to wrap the insulating layer, it can also better inhibit the penetration and damage of the environmental water pressure to the insulating layer.

[0062] In Comparative Example 2, by introducing a styrene structure to replace "sodium 4-vinylbenzenesulfonate" in this solution, although the intervention of the benzene ring can also support and prop up the crosslinked network, the single benzene ring has high hydrophobicity, and its distribution in the crosslinked network will inhibit the penetration and filling of water into the crosslinked network to a certain extent. Generally speaking, the amount of water that can finally enter the crosslinked network is reduced, resulting in a decrease in the degree of water swelling of the water-blocking layer compared to Comparative Example 1 representing the prior art. As a result, the densification effect of the water-blocking layer on the inside of the cable after swelling in water is weakened, and after being affected by water pressure for a long time, the internal insulating layer of the cable is more likely to be damaged.

Claims

1. A pressure-resistant water-blocking layer, characterized in that: The pressure-resistant water-blocking layer is formed by wrapping a water-blocking cloth in an insulated cable, wherein the water-blocking cloth comprises a water-blocking powder and a base cloth for supporting the water-blocking powder, wherein the water-blocking powder is a cross-linked copolymer of vinylbenzene sulfonate and acrylate, and the cross-linking monomers thereof comprise 15 to 30 parts of vinylbenzene sulfonate, 70 to 85 parts of acrylate, and 0.5 to 1.5 parts of a cross-linking agent in proportion by weight.

2. The pressure-resistant water-blocking layer according to claim 1, characterized in that: The preparation method of the water-blocking powder is as follows: the vinylbenzene sulfonate monomer, the acrylate monomer, and the crosslinking agent monomer are fully dispersed in water to form a monomer solution; the monomer solution is heated to a certain temperature under stirring, an initiator solution is added dropwise thereto, and after the addition is completed, the reaction is continued for a period of time, and then the solution is dehydrated, dried, and crushed.

3. The pressure-resistant water-blocking layer according to claim 2, characterized in that: The acrylate monomer includes one or a combination of sodium acrylate, potassium acrylate, sodium methacrylate, potassium methacrylate.

4. The pressure-resistant water-blocking layer according to claim 2, characterized in that: The crosslinking agent monomer includes one or a combination of ethylene glycol dimethacrylate, ethylene glycol diacrylate or dipropylene glycol diacrylate.

5. The pressure-resistant water-blocking layer according to claim 1, characterized in that: The water-blocking cloth is formed by bonding the water-blocking powder with an adhesive and laying it flat on the base cloth. When laying it flat, firstly apply a 40-60 g / m 2 After the adhesive is evenly coated with the amount of the adhesive, the water-blocking powder is then applied at a rate of 30 to 100 g / m 2 The amount is evenly sprayed on the formed adhesive layer.

6. An insulated cable having the pressure-resistant water-blocking layer according to any one of claims 1 to 5, characterized in that: The insulated cable comprises, from inside to outside, a conductor, a conductor shielding layer, an insulating layer, the pressure-resistant and water-blocking layer, and a protective layer.

7. The insulated cable according to claim 6, characterized in that: The insulating layer comprises 100 parts by weight of polyethylene, 10-25 parts by weight of polyolefin elastomer, 5-20 parts by weight of compatibilizer, 0.5-2 parts by weight of crosslinking agent, 1-5 parts by weight of lubricant and 1-2 parts by weight of antioxidant.

8. The insulated cable according to claim 6, characterized in that: The protective layer comprises 100 parts by weight of polypropylene, 5 to 15 parts by weight of polyolefin elastomer, 5 to 10 parts by weight of compatibilizer, 0.5 to 1.5 parts by weight of crosslinking agent, 1 to 3 parts by weight of lubricant, 0.5 to 1.5 parts by weight of antioxidant, and 0.1 to 0.5 parts by weight of light stabilizer.

9. The insulated cable according to claim 6, characterized in that: During the preparation and molding process of the insulated cable, the aluminum foil is first evenly wrapped tightly on the outer surface of the conductor to serve as the conductor shielding layer coaxially arranged with the conductor; the components of the insulating layer are blended and melted, and then evenly extruded on the outer surface of the conductor shielding layer, and after sufficient cooling, the insulating layer coaxially arranged with the conductor shielding layer is formed; the water-blocking cloth is evenly wrapped tightly on the outer surface of the insulating layer to serve as the pressure-resistant water-blocking layer coaxially arranged with the insulating layer; the components of the protective layer are blended and melted, and then evenly extruded on the outer surface of the pressure-resistant water-blocking layer, and after sufficient cooling, the protective layer coaxially arranged with the pressure-resistant water-blocking layer is formed.

10. The insulated cable according to claim 9, characterized in that: When wrapping the water-blocking cloth, the side of the base cloth with the water-blocking powder is facing inward.

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